If your looking to replace your heads does as tech inspector said above and it may cost less then getting a set of new heads assembled but don't quote me on that as some machine shops prices vary.

The best route if your buying a complete new set of heads you can go RHS pro action 180cc intake runner heads and they come in 64 or 72cc combustion chamber and I just put a set on my engine with a gm zz4 roller cam and they are very nice heads and worth more then my old world heads ever where. Search all your options and do with what will work best but don't jump the gun and say well this for now you will only spend more in the wrong run.

Reason I say that is I have done the quick route and then regret not doing more and then ended up spending more then what I should have and would of been less if I did it right the first time. In short terms use your budget wisely and make it match good and you should be very happy with it.